José R. Reyes Memorial Medical Center's operations started in 1945 in Manila, Philippines as a 450-bed facility known as City Children's Hospital, housed in a borrowed school building and was managed by Fe del Mundo.

It was renamed North General Hospital (NGH) because it was located in Manila, north of the Pasig River, and it became a charity hospital, still under the leadership of Fe del Mundo, serving the needs of approximately two-thirds of more than a million population of the northern half of the city of Manila.

The government of the United States of America through the International Cooperation Agency (ICA) provided aid for the acquisition of medical and paramedical equipment.

During his term, new facilities and services were established such as the Microbiology Unit, Nuclear Medicine, Family Planning, ICCU, Medicare Wing and Urology ward.

In his effort, the hospital offered training and research service, thus converting it to a Medical Center in 1982 by the power of Executive Order 851.